“Low energy nuclear reactions” or LENR is the name now given to what was initially and poorly called “cold fusion”. Over twenty years of scientific research on LENR have resulted in some instances of energy gains exceeding 10, the same value as the goal of the International Thermonuclear Experimental Reactor, which could be achieved in about a decade. Some of the key experimental data from electrochemical loading of deuterons into Pd are summarized in this paper. In the past two years, engineered LENR systems reportedly have energy gains exceeding 100. The devices, which were said to exhibit such very high energy amplification values, used gas loading of protons onto and maybe into Ni. The character and stated results of the remarkable tests are summarized. Lower gain versions of such systems are now being mass manufactured for delivery to customers during 2011. Requirements for robust validation of the performance of such devices are discussed. A comparison of the history and prospects for both hot and “cold” fusion is presented. It is concluded that small and distributed LENR sources of energy might be in common use by the time hot fusion in large central facilities is finally ready for commercialization.